1. Technical Field
The present invention relates to a jig for manufacturing a long period grating filter, and more particularly to an apparatus and a method for manufacturing a long period grating filter.
2. Related Art
An optical fiber communication system consists of an information source, a transmitter or modulator, a transmission medium, and a receiver or demodulator at a destination point. The information source provides an electrical signal to the transmitter. The transmitter comprises an electrical stage which drives an optical source to give modulation of the light-wave carrier. The optical source which provides the electrical-optical conversion may be a semiconductor laser. The transmission medium consists of an optical fiber cable. The receiver consists of an optical detector which drives a further electrical stage and hence provides demodulation of the optical carrier. Thus there is a requirement for electrical interfacing at either end of the optical link. Fiber optic communications offer major advantages over wire systems because of low attenuation and high bandwidth available.
An optical fiber cable is an optical fiber waveguide having a core of a first refractive index n.sub.1 surrounded by a transparent cladding of slightly lower refractive index n.sub.2. The cladding supports the waveguide structure while also substantially reducing radiation loss into surrounding air. The optical fiber cable corresponds to a single cylindrical glass fiber having a diameter comparable to the diameter of a human hair. The optical fiber cable acts as an open optical waveguide. Light which is launched into an optical fiber at an angle less than an acceptance angle demonstrates total internal reflection in the core of the optical fiber. Periodic structures may be incorporated into optical fibers to form optical filters.
An optical filter can be used to guide light to the core of an optical fiber causing the light of desirable wavelengths to propagate in the core of that optical fiber. One type of optical filter is a long period grating filter. The long period grating filter is manufactured by periodically changing the refractive index of the core of an optical fiber. I have discovered that the manufacturing process can be inefficient, time-consuming, and expensive.
I have found that there is a need for an improved apparatus and method used in manufacturing long period grating filters.